Conventionally, in the production of semiconductor devices, microfabrication has been carried out by lithography using a resist composition. The microfabrication is a machining process in which a thin film of a photoresist composition is formed on a semiconductor substrate such as a silicon wafer, active rays such as ultraviolet rays are radiated onto the film for development through a mask pattern in which a pattern of a device is depicted, and the substrate is etched using the obtained photoresist pattern as a protective film to form a tine concave-convex corresponding to the pattern on the surface of the substrate. In recent years, semiconductor devices have been further integrated, and active rays to be used have changed from an i-line (365 nm wavelength) and a KrF excimer laser (248 nm wavelength) to an ArF excimer laser (193 nm wavelength) having a shorter wavelength. Such a change raises large issues of influence of irregular reflection of active rays from a semiconductor substrate and standing wave. To address the issues, a method for providing an anti-reflective coating (Bottom Anti-Reflective Coating, BARC) between a resist and a semiconductor substrate has been widely studied. The anti-reflective coating is also called a resist underlayer film. For such anti-reflective coatings, many studies of organic anti-reflective coatings formed of a polymer or the like having a light absorbing moiety have been carried out because of the easy availability and the like.
Patent Documents 1 to 3 disclose resist underlayer films (anti-reflective coatings) that cause no intermixing with photoresist films formed on the top layer and with which desired optical parameters (k value and n value) can be obtained when the resist underlayer films are exposed to an ArF excimer laser, and also a desired dry etching rate can be obtained.
On the other hand, in lithography employing EUV (abbreviation of extreme ultraviolet rays, 13.5 nm in wavelength) exposure, which is a further microfabrication technique, although no reflection occurs on the substrate, finer patterning causes an issue of roughness on the side wall of a resist pattern. For this reason, many studies have been performed regarding a resist underlayer film for forming a resist pattern close to a precise rectangular shape. A composition for forming a resist underlayer film with reduced outgassing is disclosed as a material for forming a resist underlayer film for high-energy radiation of EUV, X-rays, electron beams, and the like (Patent Document 4).